1 >I was using scrollview delegate methods in my project when i didn't set the UIScrollViewDelegate in my header file.
2 >The linker error was generated because I deleted the whole .xib file once but when I added a new .xib file and tried to link it that aroused this error.
To fix this error I had to make a new project and copied all my code in that new project.There may be an easier way to do this but this is what I did to fix it.